This invention relates to a shifting arrangement for a speed changing transmission of a motor vehicle having several forward gears that are shiftable by swinging forks engaging in synchronizer clutches and pivotally disposed in the transmission case. A shifting shaft is disposed in a longitudinally displaceable and rotatable manner in the transmission case in parallel to the bearing axis of the swinging forks.
A shifting arrangement of this type is known from the German Patent Document DE-AS 14 80 679. A shifting shaft, which is disposed in the transmission case in a longitudinally movable and pivotal manner, engages by means of a driving dog, according to a preselected position, in one of three gear shift levers. The gear shift levers are connected with two swinging forks disposed in the transmission case in parallel to the shifting shaft via two thrust rods pivotally connected to them. A third swinging fork is connected directly, with respect to the drive, with the gear shift lever disposed directly above it. By means of the rotation of the shifting shaft, the selected swinging fork is also rotated and, by engaging in a synchronizer clutch, shifts the transmission gear assigned to it. The transmission gears are preselected by the longitudinal displacement of the shifting shaft in the grooves of the gear shift levers.
It is an object of the invention to provide a shift mechanism that is more cost effective and more reliable operationally by having a reduced number of piece parts.
This and other objects are achieved by the present invention which provides a shifting arrangement for a synchronized speed changing transmission of a motor vehicle. The arrangement has a plurality of shiftable forward gears, and swinging forks that engage in synchronizer clutches to shift the forward gears, the swinging forks being pivotally disposed in a transmission case. A shifting shaft is disposed in a longitudinally displaceable and rotatable manner in the transmission case in parallel to a bearing axis of the swinging forks. Shift tongues are fastened to the swinging forks and have mutually aligned grooves. A shift finger is fastened to the shifting shaft and is longitudinally displaceable in the grooves. The shift finger interacts with the shift tongues such that by longitudinal displacement in the grooves and a rotating of the shift finger, the transmission gears ar selected.
With the present invention, the shift finger of the shifting shaft interacts directly with shift tongues which are fastened to swinging forks; additional intermediately disposed transmission parts are not required.
In an embodiment of the invention, the shift tongues are pivotally connected to the swinging forks and longitudinally guided on a guide rail which is fixedly mounted on a shift rod disposed perpendicularly with respect to the shifting shaft in the transmission case. The shifting fork for the reverse gear is fastened on the end face on this shift rod.
When the transmission is constructed with an overdrive, the swinging fork of transmission gears G5/G6 is replaced by a shifting fork which is disposed on the shift rod in a rotatable and longitudinally displaceable manner. The same transmission concept can be used for a low-cost modification to implement a normal 6-gear transmission or a transmission with an overdrive.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.